Method of improving the quality of link pins



y F, A. FAHRENWALD 1,859,503

METHOD OF IMPROVING THE QUALITY OF LINK PINS Filed Feb. 6, 1929 Patented my 24, 1932 UNITED STATES PATENT OFFICE,

FRANK A. FAHRENWALD, OF CHICAGO, ILLINOIS, ASSIGNORTO' Al'llIERICAN MANGANESE STEEL COMPANY, OF CHICAGO HEIGHTS, ILLINOIS, A CORPORATION OF MAINE METHOD OF IMPROVING THE QUALITY OF LINK PINS Application filed February 6, 1929. Serial 337346.

This invention relates to an improved method of making manganesesteel parts which will have greater resistance to deformation and particularly my invention relates 5 0 a method of manipulating manganese steel castings which are to be used-as link pins in order to increase the resistance to bending and deformation of the pins.

In the manufacture of manganese steel chains for use in oil well drilling the parts commonly consist of manganese steel castings. It has been found, in use, that the link pins are liable to .be deformed by bending so that the chain eventually gets out of pitch and has to be discarded. It is proposed to remedy these defects by so treating the manganese steel castings that the parts may be subjected to heavier stresses and will retain their shape without deformation. vIt is not possible to increase the strength by increasing the diameter of the link pins because of the necessity of, at the same t me, increasing in diameter the barrel surrounding the link pin which engages with the sprocket teeth. 1 Y It is, therefore, the purpose of my invention to improve the quality of manganese steel castings by cold working the castings brought about by bending operation. Preferably the bending should take place in the plane in which bending may occur in use.

It is further the urpose of my invention to PIO idG a method for improving the quality of manganese steel castings by casting the parts in a shape initially deformed from the final shape, heat treatin the castings in the usual manner and straig tening the parts to the final desired form.

It is further a particular object of my in shape and to increase the resistance to deformation by subsequently straightening the me. p Further objects and advantages of my improved method will be more readily apparent as the invention is fully described in connection with the attached drawings in which- Figure 1. is a plan view of a manganese steel chain which may be used for oil well drilling purposes.

' Figure 1.

vention to form link pins in an initially bent Figure 2 is an end elevation of Figure 1.

Figure 3 is a plan view of the link pin as it is originally cast.

-Figure 4 is a plan view of the link pin' shown in Figure 3, showing its final form.

Figures 5, 6, and 7 illustrate modified steps of forming the final link pin.

Figures 8, 9 and 10 show a further modificatlon,

My invention has been developed and its advantages recognized in connection with the link pins used in oil well drilling chains but it will be apparent that the scope of the invention is much broader and I do 'not intend to limit myself to the specific embodiment.

which I shall describe.

Figure 1 illustrates a chain used in oil well drilling and consisting of links 1 joined by link pins 2. Each link has an integral barrel 3 surroundin a central portion of a link pin and rearw'ardly projecting pivot ears 4 and 5 receiving the ends of a connecting link pin.

.The link pin is provided with an L-shaped head 6 at one end and an opening 7'at the I opposed end through which a securing cotter pin may be passed. The pivot ears are provided with recesses 8 in which the L- shaped head 6 of the link pin will seat. The link pins are assed through the chain in alternate positions as will be apparent in The engagement between the L- shaped head 6 of the pin and the recess 8 in the link prevents the turning movement of the link pin.

The parts comprising the chain are commonly composed of manganese steel castings on account of its high resistance to wear and particularly its extreme toughness and its resistance to shock which insures it against breaking during drilling operations. However, the stretching of the chain due to its high ductility has caused serious objections. The stretching is mainly caused by the deformation, due to bending, of the link pins. It is, therefore,'des'ired to increase the resistance to deformation of the link pins in order to prevent the objectionable stretching of the chain.

I have found that the' manganese steel castings comprising the link pins may be improved quality by cold working. It is, of course, well known that cold working tion at the same time somewhat decreasing its ductility. But ithas not been heretofore recognized that the. quality of manganese steel pins may be improved by casting in one contour and subsequently by cold working change-them to the required shape previous to use. If a straight pin under operating stresses 'be'ndsto a curve of, for Instance, twenty-four inches radius, it is found that its yield point has increased to a point where it balances the operating stresses and. therefore if the pin is initially formed in a shape ,having a twenty-four inch radius of curvature or of less radius andsubsequently bent to a straight form, it will be found that the yield point has been increased thus balancing the operating stresses and the pin will subsequently not be deformed under the stresses encountered in use. i 1

I illustrate in Figures 3 and 4 one method of carrying out my invention which follows the above theory. Figure B'shows the initial form of the heat treated manganese steel casting, and Figure 4 showsthe final form after straightening in a die press or other apparatus. However, the cold working of the casting may be broughtabout in other ways, thus I show in Figures 5, 6, and 7 modified steps in the formation and treatment of the manganese steel casting. Figure 5 shows the initially heat treated manganese steel casting curved about one axis or curvature. Thiscasting is bent in a die press past the straight form to an opposite curvature from. that of Figure 5 manganese steel pins and is shown in Figure 6 while the final step involves bending the pin toa straight form.

It will be found that the cold working of the in brought about by the bending operations as .increased its resistance to deformation and it will not henceforth be bent under the stresses encountered in use. Figures 8, 9 and '10 show a further modification in which the pin is initially cast straight, as shown in Figure 8, subsequently may occur in use. Thus the link bent about one axis of curvature to the form shown in Figure 9 and finally bent back to the straight form shown in Figure 10.

It will be noted that the bendings preferably are all in the plane in which bending ins shown in Figure 2 are liable to bend in the plane of the chain since the pull is normally longitudinal of the chain. The pins are therefore bent in a plane passing through the axis of the pin and its head.

As stated my invention has been found especially useful in connection with link. pins for chains but it willbe apparent that manganese steel castin s of other forms may be improved in quality by following similar operations, therefore, the broad scope of my inventionshould be ascertained by the refer- I ence to the appended claims. will improve the qualityof steel by increasing its hardness-and resistance to deforma I- claim '1. The method of cold-working manganese steel parts prior to use which consists in simultaneously stretching the bodymetal in oneportion of the manganese steel art and compressing the bodymetal in anot erijportion of the manganese steel'part, substantially throughout the cross section thereof. I

2. The method ofimproving the quality of manganese steel castings substantially throughout the interiorcross section thereof manganese steel pins by cold working prior to use which conslsts in bending the pin from a shape in which an axis of the pin is curved to a shape in which the axis is strai ht,

whereby the longitudinal body, meta is.

stretched on one side of the axis and compressed on the other side in the plane of bendmg. g

4. The method of improving the quality of manganese steel pins by coldiworkmgprior' to use which consists in initially casting the pin with the axis thereof curved and subsequently straightening the pin to its final shape whereby the longitudinal bodyimetal on one side of the axis is stretched and on the other side of the axis is compressed during the straightening operation.

5. The method of improving the quality ofrior to use by coldworking without modi cation of the exterior dimensions thereof which consists in casting the pin in its final shape, bending the'pin about a center in a plane of the axis of the pin andsubsequently straightening the pin to its initial shape whereb the longitudinal body metal is both stretc ed and compressed on each side of the axis thereof in the plane of bending. v Signed at Chicago, Illinois, this 30th day of January, 1929.

FRANK A. FAHRENWALD.

Ill] 

